Improved Approximation Algorithms for Minimum Weight Vertex Separators

2008 ◽  
Vol 38 (2) ◽  
pp. 629-657 ◽  
Author(s):  
Uriel Feige ◽  
MohammadTaghi Hajiaghayi ◽  
James R. Lee
Keyword(s):  
Approximation Algorithms ◽  
Minimum Weight ◽  
Vertex Separators

Approximation algorithms for minimum weight connected 3-path vertex cover

2019 ◽  
Vol 347 ◽  
pp. 723-733 ◽  
Author(s):  
Yingli Ran ◽  
Zhao Zhang ◽  
Xiaohui Huang ◽  
Xiaosong Li ◽  
Ding-Zhu Du
Keyword(s):  
Approximation Algorithms ◽  
Minimum Weight ◽  
Vertex Cover

scholarly journals On the Steiner Tree 3/2-Approximation for Quasi-Bipartite Graphs

1999 ◽  
Vol 6 (39) ◽  
Author(s):  
Romeo Rizzi
Keyword(s):  
Approximation Algorithms ◽  
Approximation Algorithm ◽  
Local Search ◽  
Key Words ◽  
Steiner Tree ◽  
Minimum Weight ◽  
Bipartite Graphs ◽  
Simple Graph ◽  
Steiner Tree Problem ◽  
Stable Set

<p>Let G = (V,E) be an undirected simple graph and w : E -> R+ be<br />a non-negative weighting of the edges of G. Assume V is partitioned<br />as R union X. A Steiner tree is any tree T of G such that every node<br />in R is incident with at least one edge of T. The metric Steiner tree<br />problem asks for a Steiner tree of minimum weight, given that w is a<br />metric. When X is a stable set of G, then (G,R,X) is called quasi-bipartite.<br /> In [1], Rajagopalan and Vazirani introduced the notion of<br />quasi-bipartiteness and gave a ( 3/2 + epsilon) approximation algorithm<br /> for the metric Steiner tree problem, when (G,R,X) is quasi-bipartite. In this<br />paper, we simplify and strengthen the result of Rajagopalan and Vazirani.<br />We also show how classical bit scaling techniques can be adapted<br />to the design of approximation algorithms.</p><p>Key words: Steiner tree, local search, approximation algorithm, bit scaling.</p><p> </p>

Approximation algorithms for minimum weight partial connected set cover problem

2014 ◽  
Vol 31 (2) ◽  
pp. 696-712 ◽  
Author(s):  
Dongyue Liang ◽  
Zhao Zhang ◽  
Xianliang Liu ◽  
Wei Wang ◽  
Yaolin Jiang
Keyword(s):  
Approximation Algorithms ◽  
Minimum Weight ◽  
Set Cover ◽  
Set Cover Problem ◽  
Connected Set ◽  
Cover Problem ◽  
Connected Set Cover

scholarly journals Approximation algorithms for minimum (weight) connected k-path vertex cover

2016 ◽  
Vol 205 ◽  
pp. 101-108 ◽  
Author(s):  
Xiaosong Li ◽  
Zhao Zhang ◽  
Xiaohui Huang
Keyword(s):  
Approximation Algorithms ◽  
Minimum Weight ◽  
Vertex Cover

scholarly journals Approximation Algorithms for Connected Graph Factors of Minimum Weight

2016 ◽  
Vol 62 (2) ◽  
pp. 441-464 ◽  
Author(s):  
Kamiel Cornelissen ◽  
Ruben Hoeksma ◽  
Bodo Manthey ◽  
N. S. Narayanaswamy ◽  
C. S. Rahul ◽  
...  
Keyword(s):  
Approximation Algorithms ◽  
Connected Graph ◽  
Minimum Weight ◽  
Graph Factors

Further Studies on the Mechanisms for the Antithrombotic Effects of Sulfated Polysaccharides in Rabbits

1988 ◽  
Vol 60 (02) ◽  
pp. 188-192 ◽  
Author(s):  
F A Ofosu ◽  
F Fernandez ◽  
N Anvari ◽  
C Caranobe ◽  
F Dol ◽  
...  
Keyword(s):  
Antithrombin Iii ◽  
Ex Vivo ◽  
Thrombus Formation ◽  
Minimum Weight ◽  
Sulfated Polysaccharides ◽  
Pentosan Polysulfate ◽  
Heparin Cofactor Ii ◽  
Thrombin Inhibition ◽  
The Relationship ◽  
Prothrombin Activation

SummaryA recent study (Fernandez et al., Thromb. Haemostas. 1987; 57: 286-93) demonstrated that when rabbits were injected with the minimum weight of a variety of glycosaminoglycans required to inhibit tissue factor-induced thrombus formation by —80%, exogenous thrombin was inactivated —twice as fast in the post-treatment plasmas as the pre-treatment plasmas. In this study, we investigated the relationship between inhibition of thrombus formation and the extent of thrombin inhibition ex vivo. We also investigated the relationship between inhibition of thrombus formation and inhibition of prothrombin activation ex vivo. Four sulfated polysaccharides (SPS) which influence coagulation in a variety of ways were used in this study. Unfractionated heparin and the fraction of heparin with high affinity to antithrombin III potentiate the antiproteinase activity of antithrombin III. Pentosan polysulfate potentiates the activity of heparin cofactor II. At less than 10 pg/ml of plasma, all three SPS also inhibit intrinsic prothrombin activation. The fourth agent, dermatan sulfate, potentiates the activity of heparin cofactor II but fails to inhibit intrinsic prothrombin activation even at concentrations which exceed 60 pg/ml of plasma. Inhibition of thrombus formation by each sulfated polysaccharides was linearly related to the extent of thrombin inhibition achieved ex vivo. These observations confirm the utility of catalysis of thrombin inhibition as an index for assessing antithrombotic potential of glycosaminoglycans and other sulfated polysaccharides in rabbits. With the exception of pentosan polysulfate, there was no clear relationship between inhibition of thrombus formation and inhibition of prothrombin activation ex vivo.

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